title: Good agreement between minimal erythema dose test reactions and objective measurements: an in vivo study of human skin.
abstract: OBJECTIVE
  The erythema resulting from the minimal erythema dose (MED) test is subjectively assessed. The evaluator visually grades erythema on an ordinal scale. Both intra- and interobserver variation have been found for this erythema assessment. We wanted to examine if objective measurements could be used to confirm the subjective finding.
  
  
  METHODS
  One hundred two ultraviolet radiation (UVR)-exposed skin sites on the backs of 17 healthy volunteers were assessed. Erythema was visually graded according to a 5-point scale [0, (+), 1+, 2+, 3+] and objectively measured by a skin reflectance meter. Skin water content was objectively measured by tissue dielectric constant measurements.
  
  
  RESULTS
  The relationship between subjective assessments and objective measurements of erythema was found to be linear (R(2)  = 0.482, P < 0.0001). A positive correlation was found between subjective assessments of erythema and objective measurements of water content (Spearman's Rho = 0.414, P < 0.0001). Water content in categories 2+ and 3+ of the subjective erythema assessments differed significantly from the lesser categories (P < 0.0001). A linear relationship was found between the objective measurements of erythema and water content (R(2)  = 0.241, P < 0.0001).
  
  
  CONCLUSIONS
  Objective measurements of skin erythema and water content after UV exposure were in good agreement with the subjective assessments of erythema, but showed considerable interpersonal variation.
authors.affiliation: Department of Dermatology, Bispebjerg Hospital, Copenhagen, Denmark. mettebodek@hotmail.com
authors.forename: Mette
authors.initials: M
authors.lastname: Bodekær
authors.forename: Peter Alshede
authors.initials: PA
authors.lastname: Philipsen
authors.forename: Tonny
authors.initials: T
authors.lastname: Karlsmark
authors.forename: Hans Christian
authors.initials: HC
authors.lastname: Wulf
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D017097:Electric Impedance; D004890:Erythema / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012867:Skin / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water
keywords: MED test; UVR; erythema; skin; skin water content